Means for producing smooth acceleration in positive drive clutches



Sept. 9, 1947. j R. E. MATHl-:s 2,427,292 MEANS FOR RODUCING SMOOTHA ACCELERATION IN. POSITIVE DRIVE CLUTCHES 'Filled Deb. 1o, 1942 INVNToR. HIC/Mp0 f. Man/5 Patented Sept. 9, 1947 1 MEANS Fonrlmnncmef SMOOTH AccEL- Y ERATIQN IN-PosITIvE DRIvE cLU'rcHEs Richard E. Mathes, Silver Spring, Md., assignor to Radio Corporation of tion of Delaware America, a corpora- Application December 10, 1942, Serial-No. 468,538

There are many uses for positive drive clutches inwhich the driven shaft must reach the driving speed vby rapid and smooth acceleration. with minimum period of overrun.V One example of this' is receiving distributors in multiplex telegraphy, though the invention is not to be limited to that u'se. In such use, the distributor or other member V should start substantially instantaneously and accelerate smoothly to, and lock in at, the synchronous speed as soon as it is reached.

It is an object of my invention to provide a positive drive clutch that accelerates quickly and smoothly to the desired'speed, where it'locks in with n o overrun, to provide a positive'drive after the desired speed has been reached.

Another object of the invention is to provide a friction clutch tending to drive the. driven member above the desired speed and prevent it from exceeding the desired speed by a positively acting clutch. l

' Other objects will appear in the following description, 'reference being hadto the drawings, in which;

Figure l is a sectional elevation of the improved clutch mechanism. a Figure 2`is a. modified form of ratchet clutch for usezin the mechanism shown in Figure 1'.

Referring to Fig. l, the ldrive shaft I, driven by any means, has a gear 2 meshing with a gear 3 keyed tofshaft 4, which is journaled in a'sleeve 5 by any desired means, for example by thrust ball bearing 6. The shaft I also has keyed theren a ygear 'I which may, if desired, be made in- 7 claims. (ci. 19g-53) tegral with gear 2. Gear `I meshes with-gear y8 keyed to the sleeve 5. This sleeve is'journaled in the stationary part, not shown, in any Way; for example, by thrust ball bearing 9.

Shaft 4 has rigidly keyed thereona one-way positive drive crown clutch member Ill. This clutch member loosely fits in the sleeve .5. Sleeve 5 also has a friction clutch driving member I I engaging another friction clutch driven member I2 on sleeve I3. Sleeve I3 is journaled in the stationary part by means of a thrust bearing I4.

Sleeve member I5, the teeth of which mesh with the crown clutch engaging member II). Clutch member I5 is splined ondriven shaft I6, which is rigidly keyed to sleeve I3. Spring I1 yieldingly inaintains the clutch members IIJ and I5 together. The teeth on the crown clutch I0, I5l are so cut as to permit the clutch member I5 to ratchet over or slip when shaft 4 is rotating in the direction of the arrow I8, either while shaft I6 is stationary or is rotating in the direction of the arrow I9 kat a speed below the synchronousspeed The driven shaft I6 may be fastened to a tele- I3 contains crown clutch engaging provided from start of.' shaft 2 graph distributor, telegraph printing mechanism, or any other part.

The sleeve I3 is the member that is intermittently rotated and has -means for stopping this rotation typified by stop lever 20 pivoted at 2l in any stationary part. This stop lever. has a detent tting in a suitable depression 22 in the sleeve, in which position it is yieldingly positioned by a spring 23. The stop lever may be removed from its locking position by any means, such as a magnet ZII.

AThe operation of my improved clutch mechanism is as follows:

Let it be supposed that shaft I is driven at the desired synchronous speed and that the sleeve I3 is held stationary by the detent in notch 22. In this condition, the friction surface of the driving Amember II will slide over friction surface I2 and the teeth of crown clutch member IU will snap over the teeth in crown clutch member I5, the latter slipping to theleft in Fig.l to permit this. If it is desired to start the driven shaft. I6 and bringit quickly up to the synchronous speed of shaft 4, for example by a signal energizing magnet 24, the detent would be removed from notch `22 and sleeve I3 and crown clutch member I5 will be rotated in the direction of the arrow I9 by gears 'I, 8, sleeve 5, friction clutch II, I2 and sleeve I3. The ratio of the two trains of gears 2, 3 and l, 8 is such as tof produce a considerably rfaster rotation of gear 8 than gear 3. Consequently, the slip-ping of the one Way posi'- tive crown clutch will decrease as engaging member I5 gains ony engagingmember I0. When shaft I6 is brought up to speed of shaft 4, the teeth on clutch member I5 positively lock with the teeth on clutch member I0 and gears 'l and 8 cannot drive shaft I6 any faster because the positive clutch driven by gears 2 and 3 positively prevents this. From then on, the slippage will occur at the friction clutch II and I2 and shaft I 6 will be maintained in absolute synchronism with shaft 4.

In, my improved clutch mechanism, the slant ofthe teeth in the crown gear I 0, I5 is directly opposite to the usual slant in va positive drive clutch. That is, if there were no other means for'driving the. Vshaft I6 than by the positive clutch, the crown gear clutch would slip and not produce a positive drive. The reason for this is that the crown gear clutch member Hl,- I5 is really not a driving clutch but an overspeed clutch. vThe driving is accomplished (through the friction clutch I I, I2 which tends to drive shaft I6 at a considerably higher speed than shaft 4, but the crown gear clutch I0, I5 will not permit this so that absolute synchronism is maintained and'quick and smooth acceleration is I6 up to full synchronous speed.

While it is feasible to use a crown clutch l0, I5 as descrfbeparticularly when the teeth are made of .hardened steel or other suitable material, in some cases I prefer to use the ball or roller bearing positive clutch as Shown in Fig. 2.

In Fig. 2 the member 25 may be made the en rigidly keyed to shaft l5, as Yside play is unneces' sary in this form of clutch. As shown inthe drawing, there are seven rollers or balls 21 positioned in between the members 25 and 26, alth'ough any number of these may 'be used. There is a tooth 28, .29 on the members 25 and 25, respectively, for each of the balls or rollers and these teeth 4are so designed that the radial distance between a tooth '28 and a tooth 29 is less than the diameter of the roller or ball 21 but the radial distance between the depressions 3U. 3l at the base of th'e teeth is greater than the diameter of the ball. If member 25 is the engaging member rotating in the direction of the arrow V32, the vertical side 28, 38 of ja tooth will be the leading side and the vertical side 29, 3| of a tooth will be the trailing side. This is the reverse of the usual clutch arrangement because, as already explained, this positive clutch' is used to lprevent overrunning of the driven member and not to drive it.`

It will be apparent that when the clutch of Fig. 2 is substituted for the crown clutch of Fig. l,

the operation will be the same as already described for Fig. 1 withgthe crown clutch.

My invention is not to be limited toany form of friction or positive drive clutch, as various forms may be used for producing the same action.

Having described my invention, what I claim l. In a. transmission for transferring movement from .a drive sh'aft to a driven shaft, means including a friction clutch for tending to drive the driven shaft at a speed greater than a, desired speed, means for limiting the speed of the driven shaft to the said desired speed including a one-way positive clutch having its engaging members operatively connected between the drive and driven shafts, one engaging member of said one-way positive clutch' being drivingly connected with the driven element of said friction clutch.

2. In a transmission forY transferring movement from a drive shaft to a driven shaft, means including a plurality of gears and a friction clutch for tending to drive the driven shaft at a speed greater than a desired speed, means for limiting the speed of the driven shaft to the said desired speed including a one-way positive clutch having its engaging members operatively connected between the drive and driven shafts, one engaging member of said one-way positive clutch being drivingly connected with th'e driven element of said friction clutch.

3. In a transmission for transferring movement from a drive shaft to a driven shaft, means including a. friction clutch for tending to drive the driven shaft at a speed greater than a desired speed, means for limiting the speed of the driven shaft to the said desired speed including a one-way positive clutch `having its engaging members operatively connected between the drive and driven shafts, a hollow sleeve member fse- 4 cured for rotation with said driven shaft, a spring member located within said .hollow .sleeve to yieldingly maintain the engaging Vrru'evmbers of said one-way positive clutch in engagement, one

engaging member of said one-way positive clutch being drivingly connected with the driven element of said friction clutch.

4. In a transmission for transferring movement from af-drive shaft to a driven shaft, means inclu-dinge friction clutch for tending to drive the driven shaft at a speed greater than a desired speed, means for limiting the speed of the driven shaft to the said desi-red speed including a oneway positive clutch having ratchet engaging members operatively connected between the drive and driven shafts, one ratchet engaging member of the one 4way positive clutch being drivingly connected with the driven element of the friction clutch. y

5. In a transmission for transferring movement from a drive shaft to a driven shaft, means including a friction clutch for tending to drive the driven shaft at a speed greater than 'a desired speed, means for limiting the speed of the driven shaft to the said desired speed including a one-way positive clutch having 'its engaging' members operatively connected between the drive and `driven shafts, one engaging Ymember of said one-way positive clutch being drivingly connected with the driven element of said .friction clutch, and means for intermittently holding said. driven shaft stationary.

6. The combination of a driving and a driven shaft, a gear train connecting said shafts lfor rotation at a predetermined speed, a second gear train for connecting said shafts tendingto'rotate the same at a higher speed, and means whereby the said second train will drive the drivenV shaft at all speeds below the predetermined speed and the first said train will drive the same at such speed, comprising .a slip clutch in the second gear train and a one-way overrunning clutch in the first train` 7. A mechanism comprising a first shaft, a second shaft aligned therewith, sleeves on said shafts arranged in end to end relationship, the sleeve on the fir-st .shaft being rotatable thereon and the sleeve on the second shaft being keyed thereto, means for rotating the first shaft at a desired maximum speed, instrumentalities including a slip clutchrbetween adjacent ends of said sleeves tending to rotate the second shaft Vat a higher speed for quick acceleration to such desired maximum speed, andl a one-way :overrunning Vclutch mounted on the adjacent le-nds of said shafts for automatically clutching the same together when the rotation of the .second shaft attains the desired maximum speed.

RICHARD E. MATHEs'.

REFERENCES CITED VThe following references are of record in the file of this patent: 

